摘要
深部热液流体对川西北地区碳酸盐岩的储集性具有一定的改善作用。为研究川西北地区中二叠统栖霞组热液作用及其对储层的影响,开展了岩心观察、薄片鉴定、微量元素测试和锶同位素研究。结果表明:①川西北地区中二叠统栖霞组储层受到了深部热液流体改造,岩石中发育溶蚀孔洞,部分孔洞中充填鞍状白云岩、黄铁矿、绿泥石、石英等热液矿物,常可见热液角砾碳酸盐岩,为热液活动证据之一;②研究区栖霞组热液改造后形成的中晶白云岩、缝洞中的鞍状白云岩与未受热液改造的泥晶灰岩相比,具有"δ^18O偏负、^87Sr/^86Sr偏正和高Mn-低Sr"的特征;③研究区晚二叠世-三叠纪曾发生过多期岩浆-构造作用,大量深部热液流体通过深大断裂进入沉积地层,对裂缝围岩产生了显著的溶蚀作用,形成了良好的储集空间。该研究成果对深层寻找优质白云岩储层具有重要意义。
Deep hydrothermal fluids can improve the reservoir properties of carbonate rocks in northwestern Sichuan Basin. In order to study the effect of hydrothermal fluid on the reservoir of Middle Permian Qixia Formation in northwestern Sichuan Basin,the core and thin section observation and geochemical analysis of trace elements and strontium isotopes were analyzed. The results show that:(1)The reservoir of Middle Permian Qixia Formation was reformed by deep hydrothermal fluid. Hydrothermal minerals such as saddle-shaped dolomite,pyrite,chlorite and quartz were found in part of dissolved holes,and hydrothermal breccia carbonate rocks,an important lithofacies indicator of hydrothermal activity,were found in drilling coring.(2)Compared with limestone without hydrothermal modification,pinhole dolomite and saddle-shaped dolomite show the characteristics of delta δ^18O negative migration,^87Sr/^86Sr positive migration,high Mn and low Sr.(3)Multi-stage magma-tectonism took place in Late Permian to Late Triassic in the study area,and a large number of deep hydrothermal fluids entered the sedimentary strata through deep and large faults,resulting in significant dissolution of surrounding rocks,forming a good reservoir space. The research results are of great significance for the deep exploration of high quality dolomite reservoirs.
作者
杨雨然
张亚
谢忱
陈聪
张晓丽
陈双玲
高兆龙
YANG Yuran;ZHANG Ya;XIE Chen;CHEN Cong;ZHANG Xiaoli;CHEN Shuangling;GAO Zhaolong(Research Institute of Exploration and Development,PetroChina Southwest Oil & Gas Field Company,Chengdu 610041,China)
出处
《岩性油气藏》
CSCD
北大核心
2019年第6期44-53,共10页
Lithologic Reservoirs
基金
国家科技重大专项“四川盆地二叠系—中三叠统大型气田富集规律及目标评价”(编号:2016ZX05007004)
中国石油重大科技专项“西南油气田天然气上产300亿立方米关键技术与应用”(编号:2016E-06)联合资助
关键词
微量元素
锶同位素
角砾碳酸盐岩
热液作用
栖霞组
中二叠统
川西北地区
trace elements
strontium isotope
breccia carbonate rock
hydrothermal action
Qixia Formation
Middle Permian
northwestern Sichuan Basin
